Task Specific Project #2: FDPM Surgical Instrument for intraoperative guidance The goal of this Specific Task Project is to adapt our FDPM instrument for use in the surgical suite to locate and identify cancer positive LNs delineated by NIR dyes conjugated to targeting moieties as described in the primary project. In year three, the first instrument will be developed and delivered for use at the MEDVAMC; the second will be assembled and delivered for use at BTGH in the early part of year four. This instrument will be designed for rapidly acquired fluorescent amplitude images rather than tomography. When the phase difference between gain modulation of the intensifier and the laser diode is kept constant, a stead-state image is captured that is sensitive to the magnitude of the phase delay. If we introduce a zero and 90 degree phase change between the modulated excitation light and the detector, two different stead-state images are collected. The difference between these two images results in the fluorescent amplitude image is obtained without the confounding effect of the ambient DC light levels. This approach was employed under light levels of fluoroscopy with our work with Mallinckrodt Medical and the Lovelace Research Institute in the mid 1990s to image reactive lymph nodes in canines [90].